edit compound paths

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Modeling - Editing

Compound paths (commands)

Make two closed splines into one shape with a hole, or into one merged outline. Make Compound Path and Release Compound Path, both in the Edit menu.

Menu: Edit > Make Compound Path, Edit > Release Compound Path | In depth: Splines

Drawing a closed spline inside another gives you two shapes, both solid. Make Compound Path combines the selected splines into one spline: each becomes a sub-spline of it, and the inner ring reads as a hole. The parts keep their own geometry and stay editable where they sit.

Neither command has a keyboard shortcut.

Nesting decides a hole. Winding does not.

This is the rule, and it is worth knowing before anything else on this page.

A ring is a hole because it sits inside another ring. The direction it runs makes no difference at all. Nest a third ring inside the hole and it fills again, and so on alternating inward, which is what a pierced design with islands inside its holes needs.

If you have come from another outline tool, this is where Locus parts company with it. There, direction makes a counter: two rings wound opposite ways give a hole. Here it cannot be gotten wrong, because direction is not what is being read.

View > Show Curve Direction is honest about this. It reports the direction a path was drawn in, which is a real fact that the Pen and anchor editing both use. It simply does not decide fills. Show Region Direction never draws on splines at all.

Cut holes, or merge them

A compound does not have to cut a hole. It can merge its sub-splines into one outline instead, and the choice is a switch on the object rather than a command.

A compound's row in the Layers panel carries a small control left of the eye, reading compound or union, built the way a line row's line-or-ray control is built. Hovering it says which way round it is: Cutting a hole where sub-splines nest - click to union them instead, or Unioning its sub-splines into one outline - click to cut holes instead.

• Two overlapping rings become one shape with no seam through the overlap, and a ring inside a ring merges away rather than becoming a hole.
• It is reversible and nothing is baked. The sub-splines stay exactly as drawn and the merged outline is worked out from them, so switching back hands the parts straight back.
• It is a real union, not a fill trick. The merged outline is curve exact: no faint seam where two sub-splines overlapped, and no curve flattened into short straight runs.
• An open sub-spline joins in by being closed with a straight line between its two ends, for the merge only. It stays open in the editor, and that straight run is not an anchor, is not selectable and is never drawn as a stroke. So the same open sub-spline can union to one shape and Close Spline to a slightly different one: Close Spline curves its closing span when the end anchors have handles pointing into it, and the merge does not.
• The row's type label follows the object. A compound reads compound rather than spline, and goes back to spline when it is released. Both toggles on that row, this one and the line-or-ray one, can be undone.

What a compound is, and what it is not

• Splines only. Make refuses anything else by name rather than converting it quietly. An imported outline goes through Convert to Spline first.
• The compound takes the backmost spline's style, as other outline tools do.
• A compound has one fill. There is no way to give one sub-spline a different color from its siblings: they are outlines of a single object. Separate splines stacked are the thing to reach for instead.
• It is not the Layers panel's Group. A group holds objects that stay separate; a compound is one object with several outlines.

Release

Release Compound Path splits the pieces back out.

• Each sub-spline gets back the style it was combined with, rather than keeping the compound's. This is where Locus parts company with the tool you may know, where a released compound comes back wearing the compound's attributes.
• A sub-spline that was never a separate object, one drawn straight into the spline with the Pen, takes the compound's style, having none of its own to return to.
• The pieces land where the compound was, in the same place in the drawing order and the same folder, and a hidden compound releases into hidden pieces.
• Release is flat. If a sub-spline was itself a compound before an earlier Make, it comes back as separate splines rather than as a smaller compound. Nothing records how deep the nesting once went.
• Releasing a spline that has only one sub-spline says so and does nothing. That is not an error.

Two things it refuses

Both refuse the whole command rather than doing part of it.

• A locked spline is never combined or released. Make refuses if any selected spline is locked, by its own padlock, by a locked folder or by a node holding it, because combining rewrites one spline and removes the others. Release refuses a locked compound for the same reason.
• A spline something is built on is refused by name. If a point or anything else is built on one of the splines being combined, combining would delete that too, since the outline survives as a sub-spline while the object it belonged to does not.

In an export

A spline or a compound reaches the file now, in SVG and in DXF alike.

• Fill follows what the canvas does. Only closed sub-splines fill, nesting cuts the hole, and an open sub-spline is stroked and never filled. A drawing does not change shape on the way out.
• A union compound exports as the merged outline, because that is what it is.

Related

• Splines: what a spline is and how it is edited.
• Close Spline: closing one sub-spline, and how its closing span differs from a union's.
• Convert to Spline: the way in for an imported outline.
• The Pen: drawing a hole in one gesture, without either command.
• Regions & booleans: the other way to take one shape out of another.

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